They convert mains (AC) to whatever DC is needed by the device. There are advantages to not having the brick built in - namely it's easier to have a universal device that doesn't rely on a particular mains input (you just switch out the adapter), if the adapter fails you don't brick the entire device and can much more easily replace it, and it is bulky and gets hot and stuff, so keeping it external to the device lets it be smaller and less likely to overheat (especially useful with laptops).

Obviously the advantage of not having a powerbrick is that you don't have a goddamn awful and annoying power brick.

one bonus of a power brick is noise reduction, it was the first thing i noticed with the PS4 is that it can be rather loud when compared to the silence of the Xbox One, i assume this would be the reason or a leat the major contributeing factor

My first experience with power bricks wasn't the greatest, my brothers first ZX Spectrum had one, and one day while we were playing on it, smoke started pouring from the damn thing and it turned out that the innards had melted.

D.J wrote:My first experience with power bricks wasn't the greatest, my brothers first ZX Spectrum had one, and one day while we were playing on it, smoke started pouring from the damn thing and it turned out that the innards had melted.

I remember my Speccy power brick that after a few years of use, started to buzz like a bee. It was strange at first but eventually became a sound I associated with playing my Speccy.

Also, does anybody remember the chaos Microsoft had with the power brick on the first Xbox? The console had been out a few years when a major fault was discovered where the brick would massively over heat and in extreme cases, catch fire. MS replaced all the power bricks if you called a helpline or filled out an form online with safety ones that had a cut off switch built into them and if it detected a surge, it'd kill the power to the console. I'll never forget the phone call I made to their helpline, where wires definitely got crossed and somehow I was put through to an American woman who had no idea what I was saying. What should have been a quick five minute phone call turned into a 30 minute one where I had to speak so loud and slowly (like you do when you visit a country which doesn't speak English in the hope that they'll somehow miraculously understand you) and repeat everything I said about five times while spelling my address to her like you were talking to a 4 year old child who was learning how to spell - 2...1....A....P....P...L..etc. My God that was awful and I was nearly suicidal at the end of it.

Of course the icing for that cake was yet to come when 10 days later came a new power cord and brick with an American mains adapter ready for the American current rendering my time and phone call an utter waste. I went straight onto the website (which is what I should have done in the first place) and had a proper replacement delivered inside 5 days.

Microsoft really don't have a lot of luck with their consoles do they?!